<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>flex3</title>
<meta name="description" content="">
<meta name="keywords" content="">
<link href="./index.css" rel="stylesheet">
</head>
<body>
  <div class="list">
    <div class="item a"></div>
    <div class="item b"></div>
    <div class="item c"></div>
    <div class="item a"></div>
    <div class="item d"></div>
    <div class="item c"></div>
    <div class="item b"></div>
    <div class="item c"></div>
    <div class="item a"></div>
    <div class="item b"></div>
    <div class="item c"></div>
    <div class="item c"></div>
    <div class="item a"></div>
    <div class="item d"></div>
    <div class="item a"></div>
    <div class="item d"></div>
  </div>
</body>
</html>